This invention describes a method for increasing the efficiency and reducing the undesirable emissions of an internal combustion engine. While the general principles and teachings hereinafter disclosed are applicable to all combustion engines, the invention is hereinafter described in detail in connection with its application to a reciprocating, fuel injected, spark ignited, multi-cylinder engine.
As used herein, the term "engine" refers to a device which converts heat energy, released by the combustion of a fuel, into mechanical energy in a rotating output shaft of the engine. Also, the term "disabled cylinder" is defined as having the intake and exhaust valves of a cylinder disabled so that they remain closed while the crankshaft is rotating. These valves may be poppet valves driven by a camshaft common to such engines or any other valves which admit or discharge a gaseous mixture to or from the cylinder. Also, the term "brake specific fuel consumption" (BSFC) is defined as the amount of fuel consumed to produce a given power at the engine drive shaft.
In the United States, the law requires that many types of vehicles must be tested over a specified driving cycle (CVS test) while the fuel consumed and the exhaust emissions generated are measured. This driving cycle has many periods of acceleration, deceleration and idle, with few periods of steady speed, and is intended to reflect typical urban vehicle usage. During deceleration and idle operation it is difficult to control emissions in typical internal combustion engines--particularly throttled engines--because of the low manifold pressures at these times. Also, when the accelerator pedal is released, fuel continues to be consumed even though no energy is required from the engine. The emissions measured during this test must be less than those specified by law at the time of manufacture, and the fuel consumed is used in the determination of the vehicle manufacturer's corporate average fuel economy (CAFE).